α‐adrenoceptors: Recent developments

Rr, Ruffolo; Jm, Stadel; Hieble, J. Paul

doi:10.1002/med.2610140204

Cited by 53 publications

(36 citation statements)

References 135 publications

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“…More recent pharmacological and molecular studies have further subdivided both ␣ 1 -and ␣ 2 -noradrenergic receptors into four different subtypes, namely A, B, C, and D (Bylund, 1988;Garcia-Sainz, 1993;Ruffolo et al, 1994). In the present study, the ␣ 1 -antagonist [ 3 H]prazosin was chosen to label the total population of ␣ 1 -adrenoceptors because all known subtypes present a similar high affinity for prazosin.…”

Section: Noradrenergic Receptorsmentioning

confidence: 98%

Autoradiographic study of ?1- and ?2-noradrenergic and serotonin1A receptors in the spinal cord of normal and chronically transected cats

1999

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Section: Noradrenergic Receptorsmentioning

confidence: 98%

Autoradiographic study of ?1- and ?2-noradrenergic and serotonin1A receptors in the spinal cord of normal and chronically transected cats

1999

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“…Subsequently, a 1b , a 1c and a 1a or a 1d subtypes were identified by cDNA cloning techniques (Cotecchia et al 1988;Schwinn et al 1990;Lomasney et al 1991;Perez et al 1991). More recently, the relationship between the pharmacologically defined a 1 subtypes and the cloned a 1 subtypes have been elucidated (Ford et al 1994;Bylund et al 1994;Faure et al 1994;Ruffolo et al 1994). According to the most recently recommended nomenclature (Hieble et al 1995), three a 1 subtypes have been designated: a 1A or a 1a (originally designated as the pharmacological a 1A and the cloned a 1c ), a 1B or a 1b , and a 1D or a 1d (previously designated as the cloned a 1a or a 1a/d ), as well as an additional a 1L subtype which is characterised by its low affinity for prazosin.…”

Section: Introductionmentioning

confidence: 99%

Identification of alpha1-adrenoceptor subtypes in the human prostatic urethra

Taniguchi

Ukai

Takano

et al. 1997

Naunyn-Schmiedeberg's Arch Pharmacol

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To identify the alpha 1-adrenoceptor subtypes in the human prostatic urethra, we compared the potencies of various alpha 1-adrenoceptor agonists and antagonists in inhibiting [3H]tamsulosin binding to human prostatic urethral membranes with their potencies in inhibiting the binding of (+)-beta-([125I]iodo-4-hydroxyphenyl)ethylaminomethyl-tetralone ([125I]HEAT) to cloned human alpha 1a, alpha 1b and alpha 1d subtypes. The alpha 1A-selective antagonists 5-methylurapidil and (+)niguldipine showed higher affinities for both cloned alpha 1a and urethral alpha 1-adrenoceptors than for cloned alpha 1b- and alpha 1d-adrenoceptors. NS-49, (R)-3'-(2-amino-1-hydroxyethyl)-4'-fluoromethanesulfonanilide hydrochloride, recently characterized as an alpha 1A-selective agonist, also showed high affinity for the cloned alpha 1a subtype and urethral alpha 1-adrenoceptors. Prazosin showed lower affinity for alpha 1-adrenoceptors in the human prostatic urethra than for any of the three cloned alpha 1-adrenoceptors. Comparison of the affinities of alpha 1-adrenoceptor agonists and antagonists for human prostatic urethral alpha 1-adrenoceptors to their affinities for the three cloned alpha 1 subtypes indicated a close correlation between the affinities for human urethral alpha 1 and the cloned alpha 1a-adrenoceptors. However, prazosin did not conform to this pattern. These findings suggest that the predominant alpha 1-adrenoceptor in the human urethra is the alpha 1A subtype, and that an alpha 1L subtype which has been characterised by its low affinity for prazosin, may also be present.

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“…Our conclusion that both ␣ 1 -and ␣ 2 -adrenocpetors at the HF are engaged in feedback inhibitory of penile erection is therefore at variance with this stipulation. In addition to high-affinity to ␣ 1 -adrenoceptors, prazosin also binds to ␣ 2B -and ␣ 2C -adrenocpetors (Bylund et al, 1994;Ruffolo et al, 1994). On an equimolar basis, we observed that microinjection bilaterally into the HF of the specific ␣ 1A/D -adrenoceptor antagonist, naftopidil (Takei et al, 1999), or the specific ␣ 2B -, ␣ 2C -adrenoceptor antagonist, rauwolscine (Bylund et al, 1994), exerted comparable inhibition of LC-evoked decrease in baseline ICP or potentiation of papaverine-evoked elevation in ICP.…”

Section: ___________________________ Hippocampal Noradrenergic Systemmentioning

confidence: 98%

Involvement of noradrenergic innervation from locus coeruleus to hippocampal formation in negative feedback regulation of penile erection in the rat

Chang¹,

Huang²,

Chan³

et al. 2001

Hippocampus

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We demonstrated previously that a novel negative feed back mechanism for the regulation of penile erection, which is triggered by ascending sensory inputs initiated by tumescence of the penis, exists in the hippocampal formation (HF). This study further elucidated the role of the locus coeruleus (LC), which is the largest aggregate of norepinephrine-containing neurons in the brain and provides the major noradrenergic innervation to the HF, in this process. Adult male Sprague-Dawley rats that were anesthetized and maintained with chloral hydrate were used. The intracavernous pressure (ICP) recorded from the corpus cavernosum of the penis was used as the experimental index for penile erection. Electrical activation of the LC elicited a significant reduction in baseline ICP. Similar observations were obtained on microinjection bilaterally into the hippocampal CA1 or CA3 subfield or dentate gyrus of equimolar doses (5 nmol) of norepinephrine (alpha1-, alpha2-agonist), phenylephrine (alpha1-agonist), or BHT 933 (alpha2-agonist). Bilateral electrolytic lesions of the LC discernibly enhanced the magnitude and/or duration of the elevation in ICP induced by intracavernous administration of papaverine (400 microgram). A potentiation of the papaverine-evoked ICP increase was also observed following pretreatment with bilateral hippocampal application of equimolar doses (250 pmol) of either prazosin (alpha1-, alpha2B-, alpha2C-antagonist), naftopidil (alpha1A/D-antagonist), yohimbine (alpha2-antagonst), or rauwolscine (alpha2B-, alpha2C-antagonist). None of these antagonists, however, affected baseline ICP. These results suggest that noradrenergic innervation of the HF that originates from the LC may play an active role in negative feedback regulation of penile erection, engaging at least alpha1A/D-, alpha2B-, and alpha2C-adrenoceptors in the HF.

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α‐adrenoceptors: Recent developments

Cited by 53 publications

References 135 publications

Autoradiographic study of ?1- and ?2-noradrenergic and serotonin1A receptors in the spinal cord of normal and chronically transected cats

Autoradiographic study of ?1- and ?2-noradrenergic and serotonin1A receptors in the spinal cord of normal and chronically transected cats

Identification of alpha1-adrenoceptor subtypes in the human prostatic urethra

Involvement of noradrenergic innervation from locus coeruleus to hippocampal formation in negative feedback regulation of penile erection in the rat

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